Interlocking system for railroads



June 28, 193s. A] AN DoN 2,121,803

INTERLOCKING SYSTEM FOR RAILROADS Original Filed July 22, 1936 2 Shets-Sheet 1 INVENTOR 2'21- June 28, 1938. A. LANGDON' mmmocxme SYSTEM FOR RAILROADS 2 Sheets-Sheet 2 Original Filed July 22, l956 III-I'll llllll II lllll'l lll |lllll|ll u v Lu M T a I? In m Wv i: H ll| I? JII FEQQ

l E E INVENTOR d. 062/ BY M ATTOIIQNEY" vention applies to a single track switch instead of V a crossover, will be pointed out hereinafter by describing those parts of the present disclosure which may be readily omitted when only a single is controlled by a system con- 7 structed in accordance with the present invention.

trol panel also includes an entrance for each of the signal locations, such The signals 2, 3, i and are assumed to be color light signals giving the usual indications of green for clear and red for danger or stop, and yellow if an added indication is desired for caution. I-Ioweven'thesesignals may be of the searchlight type, the semaphore type, or any other suitable type instead of the type chosen for the embodiment of the present invention.

The track layout hasbeen shown as dividedinto two track circuits 6 and l by insulatedjoints, which track circuits are provided with the usual track batteries and track relays of which track relays ST and TT have been shown. These normally energized track circuits are wired in the usual manner to provide for fouling protection and to provide for the insulation of the track switches, such details of wiring having been omitted for the sake of simplicity in the disclosure. Y

The crossover including track switches TSA and. TSB is shown as having a single switch repeating relay WP of the polar neutral type. This relay WP is energized with one polarity or the other'in accordance with the normal and reverse locked positions of the track switches TSA and TSB and the switch machine SM in corresponding positions, and is deenergized Whenever the track switches are unlocked or are in operation. The polarized circuit for controlling such a switch repeating relay may be governed by any suitable means, such as ordinary switch boxes, but is preferably governed through the medium of a point detector contact mechanism such as shown for example in the patent to C. S. Bushnell, Patent No. 1,517,236,.filed November 25, 1924, it being understood that there would of course be two such mechanisms when two switch machines, such as switch machine 'SM, are employed.

Control pancL-A control machine in the central ofiice is provided with a control panel on which is located a track diagram corresponding to the actual track layout in the field. The crossover in the field is represented by a miniature crossover ts which is movable to normal, or reverse positions by electro-magnetic means including normal and reverse operating coils N and R of the magnetic operator MO. The conbutton NB as entrance buttons 2NB, 3NB, ZNB and 5NB for the respective signals 2, 3, i and 5. An exit button X3 is also provided for the end of each route, shown specifically as exit buttons 2XB,'3XB, iXB and 5XB. It isto be understood, that the ends of the route may or may not correspond to the location of the exitbuttons on the miniature track diagram, as a route is usually consideredto extend details have been shown from one particular signal to the next signal governing trafiic in the same direction or to some arbitrarily chosen point.

Each entrance button NB is in the form of a knob which is rotatable 'from a normal position to an operated position. The operation of this knob 99 inia clockwise direction operates suitable contacts to close a circuit which energizes its corresponding entrance relay. This has been merely indicated by a dotted line, as the in the above mentioned prior application of S. N. Wight, Ser. No. 69,905, filed March 20, 1936. 1

Within each entrance button NB is a suitable signal indicator SK which is illuminated whenever and only when its corresponding signal is indicating clear. Thus, the indicators ZSK, 3SK, lSK and 58K indicate the cleared condition of their respective signals 2, 3, 4 and 5, all of which is accomplished through means not shown in the present disclosure for the sake of simplicity, although reference may be made to the above mentioned application, Ser. No. 69,905, for the details of such control.

The exit buttons XB are of the self-restoring push button type which have been shown as connected to the contacts which they operated by a dotted line so as to make the relationships more readily apparent.

The track diagram also includes track indicators BTK and 'lTK which are illuminatedwhenever the corresponding track sections are occupied by'a train as. indicated by the track sections are occupied by a train as indicated by the track relays ST and IT respectively. The control for these indicators is-assumed to be of any suitable type and has been omitted from the disclosure for the sake of simplicity.

Beneath the movable points of the miniature crossover ts, are lock'lamps LKA and LKB corresponding to the respective switch points TSA and TSB, which lock lamps are illuminated whenever the crossover TS is locked against operation, or is being controlled to a new position, all of which will be described in detail hereinaften' An emergency switch control lever SML is also provided to control the operation of the switch machine SM under certain emergency conditions hereinafter pointed out in detail. This lever may be suitably located upon the control panel, or

maybe located on the back of the control machine, as desired, because of the lever is only used for emergency conditions. This control lever SML has associated therewith an indicator lamp COR which illuminated whenever the crossover TS is in midstroke position or is out of correspondence with its switch machine control as set up by the composite route control or by the emergencylever SML.

Route reZays.-The control ofiice equipment also includes a route relay for each of'the routes. These route relays are selectively controlled by the entrance'and exit buttons NB and KB, as pointed out more in detail hereinafter, and include relays-3'5, 2-5 and 24 for controlling traific between the signals represented by the numbers in such route relay reference characters. V r

The route relays provide for the positioning of suitable switch control relays WNA, WR and VINB, which relays control the operation of the switch machine SM. Associated with this control for the switch machine is a lockrelay L which prevents the operation of the switch machine fact that such,

arous I a s-unsa s r. m m w ene TSA nd orea rat d-w i o -Relays N R andBCR a re provided to indicate.

\vhen the track; switches are in correspondence eir control .as will-be pointed out herein;

tro c ear-ingot; the signals through suitable Cl selections which control the signal re? ll) lay zG-fsGgdG and SGiorg the respectivesignals indicated by the preceding numerals. g

;,In aninterlocking system, there is usually-suit able approach locking-and route clocking associated with. the signal and switch controls and 1.5 this disclosure. considers the 7 application of any suitable-route looking to the: system of: the present invention-, but for.,the purpose of illustration; directional stick relays; GES, 6W8; IE8 and 'IWS.

are'associated With'the track circuitsifi' and 1 re- Q: spectively, to, provide what is termed :rearre.-

leaseroute locking all of which 'has been. disclosedwin the prior application of. Larry et a1. Ser.

No. $17,504, filed November v2'7, 1931, to which reference may be made for the details of the con- ;;trol for such relays. V V

Itis considered sufficient for an understanding of ifl'le present invention to know that the relay 6ES-,-for example,is deenergizedi when thezsignal 2 iscleared and is maintained. deene'rgizedalthough thesignal is returned to stop so long as a V train is on the track circuit '6, but during such deenergized condition of the relay BES, the relay GWS remains picked up; Similarly,':the relay GW Sis deenergized when the signal 4 is cleared 3. and remains deenergized so long as a train: is on. Y the track circuitfi although the signal 4 is restored to stop, but during such deenergized condition of relay BWS; therelay BES remainspicked up.

4a Likewise, the relay 'IES is deenergized when- 7 ever the signal 3 is cleared and is maintained deenergized although the signal, is .returned to stop so long as a train is on the track circuit 1,

but during such deenergized condition ofnthe 4-5;, relay 'lES, the relay 'IWS remains picked up. Similarly, he relay 'IWS is .deenergized when the signal 5 is cleared and remains deenergized so lon'g .as a train is on zed condition of the relay 'IWS,

the relay 'IES remains picked 'up.

'I t is also noted in this connection that when the track switches TSA and TSB are in reverse positions to allow traflic to pass over the cross- 551'; over and the signal '2 is cleared both the relays BES and IE3. are deenergized; andi'similarly, when the signal 5 is cleared for traffic in an opposite direction over the crossover both the relays" GWS-and 'IWS are deenergized.-

It is believed that the remaining features of the present invention will be best understoodby considering the} detailed operationof 'thesystem.

Normal .conditions.'--- Although, the track switches TSA andTSB are usually left in their ofigilas-t cperatedpositions, they-have been shown in J positions for the passage of main line tramc:

'I hesignals are of course normally at-stop the loweror red indicator of each signal with normallyv illuminated, unless approach lighting myfeaturesare' employed in. accordance with the usual practices. Withthe track sections 6, and l unoccupied,

the-track relays ST and TTJare of course normally picked up.

75:; Thelockxrelay L, thel directional;stickrelays? their operations; .1

. Entrance-emit ,route ,z'nterloclaerwhen op- V, V a the track circuit I, ali V thoiighthe signal 5 is restored to stop, but dur- 503 ing such deener 6E5}, 26W an iflWS and t e p u ar co -r respondenoe relay R or ,RCR. forthepositio-n; of the track switchesf TSA and T33 are. normal-1, energized, but ;these ,circuits ;will be pointed out .-in,-d ta n connection with the-description ofv 5i the central-edifice and the indicatorson the control panel are normally All; the route. ists :inf,

deenergized to provide What has been convenient: 1y termed a, ..nor r na;lly, dark board. 1-.Qi.

' orator desires tosetuparoute from thesignal 2.-

to.;th -e signal ,ior example, he rotates the entrance, buttonrZNB 190 infla clockwise ,directionwhich close s, suitable contacts to energize: 1355 its repeating relay 2N3, in which position the;

entrance button 2N8 remains until manuallyrestoredito put therouteWhich it governs to stop as later described, After actuating the entrance-5 button the operatorthen glances along the miniature trackw-ay and finds. that there are .410;

lock lamps LK ,-illuminated .-ibetween such;. en; trance button iNB and the exit button which designates. the end of the route whichhe desired to; set up. If. a .locklampgsuchtas lock lampLKA, is illuminated? withrthezgiminiature;

crossover its in a position opposite to the-positionrequired -ior the desired route, then the operator is 'gadvisedgthat he' cannot set up the new route. 7

not illuminated and that the -miniature crossover ts is in anormal position (or it :might be in areverseg position), the operatoractuates 'theexit button4X'B. g

The contemporaneous operation of the en 3.5-; trance buttonriNB-a'nd-the exit button IXB closes apiclt-up; circuit'for theroute relay 2-4;-from. through; a circuit including front. contact. I0 of relay 2N3, back contact of route relay- 2-5, windings of route relay 25-4, back con 40 I tact 12 of relay-dNR, backcontact l3 of exit button 4 KB, to The, current which flows in; this ocir cuit causes the polar contacts of the route relay 2-4 toybeoperated to right-hand positions and: the neutral contacts to be picked'='up. As soonias the contactsof the route relay 2-4, respond, a stick circuit --is closed. from"(+'), through a circu-itfiincluding front contact Ill-.of -1elay 2NR back-contact ll of route relay 2+5,

Windings .-o f noute relay 2-'4'-, polar contact I 4 of, 59:3

t e a 2* ll. .3 e i h rha d P af on ct e ft-ro ts r ar e to Each: of the remaining route relays'a3--5' and} 2+-15 are picked .up; in a-;similar mann r andare i maintained energized dependent upon stick-cir=. 5'53 cuitswhichiare wholly dependent upon the return of their respective; entrance buttons to vinormal atfi op positions. Suchcontrolfor these re-:

mainingproute relays will. be readilyqap'parena from; the-.drawings-and' will not be described in? 60;

detailv .The :pickingup ofjthe route relay -2.--'4 opens:

-1 itsjback contact-:1fi'whichcprevents the picking up of the route relay 2-5 for establishing a con-- flictin'g routev over -.the;cr.ossover. Similarly, the

pick-sup .circui-tafor the route relay 2 -5 alsouin u cludes.:back:contact FIE-Of. route relay 3--'5; so that, theroute; relay. 2'-.-.-51='cannot be picked up; when-i I eyeritherewarerp rallel routes established .by'either 5 orbothrofithearoute relays" 3:-t-5 and 2-'-'4, J0?

.IIt is also ap'parent that the pick-up circuit or. thBL-EOlltQIBlHJYLZL-e-fl includesbackcontact? of routetrelaylei-l'n sozthatif suchroute relay"'l=-1 5: werelpickedup-ior :the-establishingof arouteioverti the crossoyersthattherroirte.relay: 2.-14.:,coii1dLnotu '75:

However, assum ng'that the lock lamp; LKA, is. 301

be picked up. A similar interlock is provided between the route relays 3-5 and 2-5 by the back contact I8 of the route relay 2-5.

In brief, it will be apparent that any number of route relays for parallel or non-conflicting routes may be picked up at the same time, while only one route relay from among a plurality of route relays for conflicting routes may be picked up at circuit including front contact 26 of relay 2-5,

any one time.

Switch control.For each crossover, a switch control relay WNA is provided for one end of the crossover in a normal position and a relay WNB for the opposite end of the crossover in a normal position, while a switch control relay WR is provided for both ends of the crossover in reverse positions. 7

The route from the signal 2 to the signal 4 requires thetrack switch TSA to be in a normal position so that the picking up of the route relay 2- 4 provides for energizing the switch control relay WNA by a circuit closed from through a circuit including front contact l9 of route relay 24, bus wire 20, windings of relay WNA, back contact 2| of relay WR, to

The picking up of the relay WNA closes the normal operating circuit for the switch machine SM from through a circuit including front contact 22 of track relay IT, front contact 23 of track relay 6T, front contact 24 of lock relay L, front contact 25 of relay WNA, through the switch machine SM, to 4 If the route relay 2-5 were picked up, which requires the track switches TSA and TSB to be in reverse positions, a circuit would be closed for energizing the relay WR from through a bus wire 21, back contact 28 of relay WNA, windings of relay WR, back contact 29 of relay WNB, to

The picking up of the relay WR would close the reverse operating circuit for the switch machine SM from through a circuit including front contact 22 of relay 1T, front contact 23 of relay 6T, front contact 24 of relay L, back contact 25 of relay WNA, front contact 30 of relay WR, through the switch machine SM, to

On the other hand, if the route relay 35 were picked up, which requires the track switch TSB to be in a normal position to establish a route from the signal 3 to the signal 5, a circuit would be closed for energizing the switch control relay W'NB, from through a circuit including front contact 3| of relay 3 5, bus wire 32, back contact 33 of relay WR,-windings'of relay WNB, to

The picking up of relay WNB would apply energyto another normal operating circuit for the switch machine SM, closed from through a circuit including front contact 22 of track relay 1T, front contact 23 of track relay 6T, front contact 24 of relay L, back contact 25 of relay WNA, back contact 30 of relay WR, front contact 34 of relay WNB, through the switch machine SM, to

From this description it will be understood that either or both of the switch control relays WNA' and WNB may be energized at any one-time, so that, when the relay W'NA is energized at the same time with the relay WNB, or alone, the switch 70" machine SM is controlled to a-normal position through the contact 25, but when the relay WNB is energized alone the switch machine SM is controlledto a normal position through the contact 34; But neither of these relays WNA or WNB can be energized when the relay WR is picked up because of contacts 2| and 33. Also, the picking up of the relay WR causes the operation of the switch machine SM to a reverse position through front contact 30, which relay WR can be picked up only when both the relays WNA and WNB are deenergized by reason of contacts 28 and 29.

The bus wires 20, 21 and 32 are not only controlled by the route relays shown, but are also selectively energized by any other route relays which may govern traffic over the track switches TSA and TSB.

Returning now to consider the operation when the route relay 2-4 is picked up and energizes the relay WNA, the closure of front contact 35 of relay WNA energizes the lock lamp LKA over wire 36, while the closure of front contact 31 completes a circuit for the magnetic operator MO from through a circuit including back contact 38 of relay WNB, front contact 31 of relay WNA, wire 39, to the normal operating coil N of the magnetic operator M0, to This energization of the normal winding N of the magnetic operator MO causes the miniature crossover is to be operated to a normal position, if it is not already in such position When the crossover, including track switches 'TSA and TSB is in a normal position, then the contacts of the relay WP are in positions as shown so that upon the picking up of the relay WNA, the lock relay which is normally energized, is immediately deenergized.

More specifically, the lock relay L is normally energized by a circuit closed from through a circuit including front contact 40 of relay 6T, front-contact 4| of relay 1T, back contact 42 of relay G, back contact 43 of relay 3G. back-contact 44 of relay 4G, back contact 45 of relay 2G, back contact 46 of relay WNB. back contact 41 of relay WR, back contact 48 of relay WNA, windings of relay L, to Thus, it is readily apparent that the energization of the relay WNA opening back contact 48 causes the relay L to drop away with relay WP indicating the normal condition of the crossover.

On the other hand, if the crossover is indicated by the relay WP as being in a reverse position upon the picking up of the relay WNA, a stick circuit is closed for the relay L from the back point of contact 41 through front contact 48 of relay WNA, polar contact 49 of relay WP in a reverse position, front contact; 5|] of relay L, windings of relay L, to The relay WNA then causes the normal operation of the switch machine SM which unlocks the track switches TSA and 'I'SB deenergizing the relay WP, which closes back contact 5| to shunt the polar contact 49 in both of its positions so upon the track switches TSA and TSB assuming normal positions, the polar contact 49 responds first to the energization of the relay WP so that the stick circuit for the relay L is maintained through front 1 contact 48, back contact 5|, polar contact 49 in a right-hand position, and front contact 50 of relay L, until the neutral contacts of the relay WP pick up, at which time the stick circuit for the relay L is opened and the lock'relay drops away.

The dropping of the lock relay opens contact 24 which prevents further operation of the switch machine SM.

The normal correspondence relay NCR is energized by a circuit closed from through a circuit including back contact 52 of the relay WR, polar contact 53 of relay WP in a rightings of relayNCR, to s V a Signal*control. -Upon the completed response oi' thetrack switches TSA and TSB and the lockihgfdf such' track switches by the dropping of thel k relay L, a signal clearing circuit is closed from f tastes of relay L; from contact '56 of relay NCR,

wire .i-I, front contact 58- of route relay 2-4, polar contact 59 of route relay 2-4 ina right-hand position; wire 60, windings of relay ZG, to The picking up of the relay 2G causes the change of the indicationof' the signal 2 from stop to clear infthe usual manner. 7 c

It is tobe understood that the signal 2'may have automatic contiohand may also be made a 'stick signal, or have other features of signalling employed therewith, although such features have been omitted from the present disclosure for the sake of simplicity.

- The clearing of the signal 2 is indicated to the operatorby the illumination of the signal indicator'2SK through meansnot shown in the drawing s". I I s 7 7 It is readily apparent'that if the operator restores the entrance button ZNB to its normal position, that the route relay 2-4 will be deener- 'giz'ed opening front contact 58 thereby restoring thegsi'gnal 2 to stop immediately upon such operati en. *I-Iowever, the route cannot be changed until a predetermined time thereafter providing to the removal of energy that a train is in approach to thesignal 2, as contemplated in accordance with the usual ap- V proach locking practices although this has not been shown. I i "Passage of a, tfaime-Assuming that the signal 2"; cleared and that a train passes over the route thus established, the deenergization of the track relay 6Tfcauses the track indicator BTK on the diagram to be illuminatedadrelay opens front contacti23' which removes energy from the switch machine SM, in addition at open front contact ascri e lock relay L; The: look relay L is also ma tained deen ergizedcby the further opening of its" circuit at Contact of relay 6T. Thus, so 16' :g as a train'is on the track section 6, theswitch machineSM'is positively prevented from operation. s

The entrancejofthetrain onto the track section er-o re y-S 5. mayfautor'natically put the signals to stop through means not shown in the present disclo-" but the operation under such circumstances nee button 2NB' toits normal position while the route .is still,occupied. Assuming that ent ce" button ZNBjhas been returned, the; route 2 -4 and the j signal relay 2G drop away i i 'i tt' gthe signal ,2 at stop; but the relay L does track relay 6T maintains the lock" indicator LKA illuminated by energizing thebus wire 36 through back contact 6|, I Thus, so long as the train is on the track sectioncfi andthe track switch TSA' is locked against operation, such condition is indicat'edlth the cperatorgby the illumination of the :route. lock indicator LKA'.

1 'I n"those, tracklayouts that have a plurality of track sections between the entering point of the route'andthe; exit of such route, each such track .secti jhas itsj directionalstick relays, such as Sand BWS; associated therewith, to lock ith switchesin the route" s'set forth'in the through a circuitincluding back con ab'ovmentioned'prior application Ser.No'.-57'Z,504'. Although the entrance button 2NB is returned to 'stop'and 'thetrain is on but the first track section in suchroute, the lock lamps such as LKA for'all 'of the track switches in the route are maintained energized by reason of the fact'th'at their respective directional stick relays'for the proper direction, such as relay BES; are all deenergized energizing their respective lock lamps .in a similar manner as closure of back contact 62 of relay EES energizes the lock lamp LKA.' .When' the train passes through such track layout, re'-' leasing the route locking in the rear of'the train by the picking upcof the track relays forthe'track sections in the rear of the train and also picking up the corresponding directional stick relays, then the switches in the rearof the train are released for use in new routes and their lock lamps are unilluminated. I Thus, the inclusion of the diagrammatic and fragmentary showing of the directional stickrelays GES, BWS, IE8 and 'lWS is to show thatthe illumination of the lock lamps, such as locklamp LKA, are dependent not only upon the occupied condition of their associated track sections but also upon the route locking conditions. The track layout shownin Fig. 2 does not require rear release route looking, asdiagrammatically indie cated, and the back contactsof thetrack relays 6T are sufiicient for thecontrol of the route lock lampsfin addition to the control by relays WNL WR- and WNB, but it isto be understood that the principles or" the system of the present invention maybe applied tojany type oftrack layout,,an'd for this reason the directional stick relay control hasbeenshown. v V f Electric.lo'clc equivalents-Let us assume that a train as passed onto the track section in responsefto a 'clearediroutejand thedeenergization ofrelay'fiTimaintains'the crossover lockedag ainst eration; but the operator has restdred the en tr'nce button 2NB', which cleared such'route,

to its normaljposition and inadvisably operates the entrance button fiNB in a counterclockwise direction 90 to an operatedposition, and then actuatestheexit button ZXB in spite of the fact that'the lock indicator LKA is illuminated; The

relay SNR repeats the button 5NB, as previously 7 discussed. ,Thefroute relay 2--5 is energized by a circuit closed from through a circuit in:

cluding front contact 63 ofrelay ENR 'backcQntact 16 of relay 24,windings of relay2-5, back contact I! ofrelay 3-5, back contact 64 ofrelay 2NR, back contactlifi of exit button 2XB. As soon as the route relay 2- -5 picks up,-its stick circuit is closed from through a circuit including front contact 63 of relay 5NR, back contact l6 of relay 2-4, windings of relay 2- 5, back contact I! of relay 3-5, polar contact GBof relayf2--5 in a left-hand position, front contact 6Tof relay 2- -5, to

The picking up ofthe route relay 2-5 closes front contact 26 energizing the relay WR, but the closure of front contact 30 cannot energize the switch machine to cause its reverse operation because the front contact 24 of the lock relay L is opened and also because the front contact 23 of thetrack relay ET is opened 7 Letus assume that the operator maintains the route'relay 2-5 in-its operated position, as just described; by allowing to remain in an operated position, then upon the the entrance button 5N3 V departure ofthetraih from the track section'fi,

th'e relayfiT picksiup closingfront Contact 23 for in part preparing the-circuit for'the switch machine SM. However, the lock relay L does not pick up upon the closure of front contact 40 of the relay 6T because the pick-up circuit for the relay L includes back contact 41 which at this time is open because of the energized condition'of the relay WR.

In other words, if an operator endeavors to set up a route which is in conflict with an occupied route to thereby precondition a new route, such new route will not be automatically set up when.

the first route becomes unoccupied. In order for the second route to be set up, the operator must restore the entrance button 5NB to its normal position deenergizing the route relay Z5 and the switch control relay WR so as to close the pick-up circuit for the lock relay L. As soon as the lock relay L has picked up, then the operator may again actuate the entrance button 5NB and the exit button 2XB causing the picking up of the route relay 25 and the energization of the relay WR'so that the reverse operation of the switch machine SM occurs in the usual manner followed by the clearing of the signal 5.

For example, the switch machine SM operates in response to the closure of front contact 30 and the reverse correspondence relay RCR is energized upon the completed response of the track switches TSA and TSB by the closure of a circuit from through a circuit including back contact 38 of relay .WNB, back contact 3'! of relay WNA, polar contact 68 of relay WP in a lefthand position, front contact 69 of relay WP, windings of relay RCR, to

The relay NCR is of course deenergized because of open back contact 52 of relay WR and open polar contact 53 which is now in a left-hand position. The lock relay L is held up by its stick circuit including front contact 41 until the neutral contact 5| of the relay WP picks up upon the operation of the switches TSA and TSB to reverse positions. The dropping of the lock relay closes the signal clearing circuit from through a circuit including back contact 55 of relay L, front contact 10 of relay RCR,'wire H, front contact 12 of relay 2-5, polar contact 13 of relay 25 in a left-hand position, wire 14, windings of relay 5G, to The energization of relay 5G causes signal 5 to change its indication from stop to clear in a manner well understood by those skilled in the art.

With the reverse switch control relay WR picked up, it is readily apparent that both of the lock lamps LKA and LKB are energized as the front contact 75 of the relay WR applies to the wire 36 while the front contact 16 of relay WR applies to the wire 17. Also, the closure of front contact 52 energizes the reverse winding R of the magnetic operator MO over the wire 18, which positions the miniature crossover is in a reverse position. This route may be put to stop simply by the restoration of the entrance button 5NB to it s normal position in a similar manner as described for the restoration of the signal'2.

It is thus readily seen that the electric lock equivalent is provided for a system of entranceexit type interlocking in such-a manner that the effect of the electric lock equivalent is removed simply upon'the restoration of the entrance but-' ton to its normal position, which is a distinct advance over thosemethods of applying such features to a system of this type thus far known, as in prior systems, the rendering effective of the electric lock equivalent, would require the additional operation of the emergency switch control lever SML in order to restore the system to a normal condition.

Emergency switch controL-The individual manual control of track switches in an interlocking plant is at times desirable under certain emergency conditions which may arise, such as the operation of a track switch back and forth when it fails to entirely complete an operating stroke by reason of ice, lumps of coal or the like. Also, it is sometimes necessary to mechanically set up a route through the plant for the passage of hand cars and the like, although it is not desired to clear a signal for such a route. This manual control is provided in accordance with the present invention so as to be possible only so long as the track switch may be actually operated, but when it is under the control of a route relay, or is locked by reason of the presence of a train, such manual control is prevented.

This manual operation of the switch machine SM is accomplished by. operating the lever SML to the right or to the left from a normal central position. When lever SML is operated to the left, it energizes the bus wires 20 and 32 to energize both of the relays WNA and WNB. The closure of front contact 25 of relay WNA is then effective to cause the operation of the switch machine SM. The lever SML provides for the picking up of both of these relays so that both of the lock lamps LKA and LKB will be illuminated while such manual control isin effect. It is noted that such energization of the relays WNA and WNB could not be accomplished if the route relay 2-5 were picked up energizing the relay WR.

The operation of the lever SML to a righthand position energizes the bus wire 21 which causes the relay WR to be picked up to cause the reverse operation of the switch machine SM by reason of the closure of front contact 30. It is noted that the relay WR could not be energized if either or both of the relays WNA and WNB were picked up in response to control by a'route relay. The energization of the relay WR. likewise illuminates bothof the indicator lamps LKA and LKB. Relays WNA, WR and WNB also control the miniature crossover ts'in'the usual way under this manual control. If either or both of the track relays GT and ET are deenergized, it is absent, and the track section 6 is then arranged to include all of the track on the turnout up to the signal 5. w e V In thecontrol office, the miniature track diagram is accordingly modified omitting, the em trance button 3NB and exit'button 3X3. The route relay 3-5 is also eliminated from the control circuits and all of its contacts removed from the circuits in which they are included in accordance with the principles of circuit Work. The switch control relay WNB and its associated connections are also. eliminated together with the indicator which it controls. It is believed that this simple statement for the centroid a single track switch is adequate to anunderstanding of how the present invention is employed with a single-track switch, and is also adequate for'a V areas-soc track switch; 7

Having thusldescribed' an interlocking system of theentrance-exit route type, as one specific embodiment of the 'presentinvention, it .is'to-be understood that various modifications, adapts -tions=,:and. alterations-may be. applied to meet the requirements.oiapractice without in any manner .departingfrom the spirit or scope of the invention except as limited by the appended: claims. Y

I What I claimis.:-

f 1-. In a centralized traflic. controlling system iorrailroadsa track switch, a switch machine ion operating said track, "normal 'and reverse switch control relays for respectively causingthe normal and reverse operation of said switchmachine,,a. locking relay for preventing the response of said switch machine to said normal and :re-

- verse switch control relays when such 'loc'king relayis deenergized, a pick up circuitifon said locking relay including hack contacts .of. said 'normal 'and' reverse switch control relays, and. a locking relay including a tick circuitfor' said 7 4 front contactof said locking. relay and contacts which complete such stick circuit only'while; said normalan'd' reverse switch control relays and said track switch are out of correspondence.

has

2'. In a' centralized trafiic controlling system for 1 railroads, a track switch,:a switch machine for operating said track switch, a traflic .relayf'or manifestin'g traihc' conditions adj acentsaidtraclt switch, normal and reverse swltchcontrol' relays for respectively" c'ausingflthe normal and reverse operation of said'switoh machine, a lockinglrelay for preventing the response: of said switch; ma

' chine to said normal and reverse ,switc'h'control relays-when'such locking relay is'deen'ergized, a pickup circuit for said locking relay including backcontacts of said switch control relaysandstront contactof said trafil'c relay; and a sticlicirg mm; for said'locking relay including a front-contact' of said locking relay, contacts which-complete such; stick circuit only while said':'n'crmal and reverse switchcontrol relays and saidtrack switch are-out of correspondence,"'and-a front contact of said traflic relay.

crossover: including twoztragc'lc s 3'. In a centralized tra'fiic controlling system for railroads; two main line tracks connected by. a crossover including two track switches;- power driven means for operating the track switches, a

normal" switch control relayfor the track switch in one main line for causing the normal operation of saidpower' dri'venjmeans for'thattraclg switch, another normal" switchcontrol'relayi for causing thenormal' operationpf said power driven means g 'I'orthe trackswitch-in-the other 7 c v p nv ne a everse switch control-relay for cau operation of said power to said switch control lrelays whenfsu'ch locking relayqis-deenerg'ized, afpickfup circuit me a-1st locking relay including back contacts of all -said switch control relays, and a stick vcircuit for said "locking" relayincluding a n said locking" relay and contacts which complete such"sticl' circuit, only while saidv switchicontrol front contact 1 of relays and saidswitches'" e e u or co 4*. his. centralized traili c'controllingsysteni ior railroads;- two; main line itracks, cor

driven means n "pperating' the; track sw'i c 7 es;

one stenc -nay rurmanifesting tram -comrades :of'said traffic relays, an 1ndicator lamp controlled icy multiple front contacts on said one normal V w swgtohcontrcl'relayalso in multiple with'a baol;

singthe reverse f contact of said another traffic relay; riven means for both 6. In a centralized traflic controlling of" the track switches, a'locking relay fcr'pre h I venting the response of said power driven means 'for railroa-ds, a'track switchg'a switch mach e foif 0 ope'ra'tingjsaid track'switch, switch control relay 1 switch machine to said switch control relay means when such locking relay is' deenergized ;.,an:l ;a'stick circuit for said 'lockingrelayn inga front contact'of said locking relayjajnd co switch are'out'of corresponde'nce f lay for said another track switch for causing the normal operation of its said power driven means, 7

'a'reverse switch control relay for causing the reverse operation of said power driven means for 10 both the traclc switches, a locking relay for preventing the response of said power driven means to said switch control relays when such locking relay is deenergized, a pick up circuit for said; looking relay including back contacts of all said switch control relays and front contacts of both saidtraihc relays, and a stick circuit for said locking relay including a front contact of said locking relay, contactswhich complete such stick 1V circuit only while said switch control relays; and 120 said track switches are out of correspondence, and front contacts of both of said traffic relays.

5. In-a centralized traffic controlling system for railroads; two main line tracks connected by a main line for causing the normal operation of its said power driven meanaanothernormal switch track switchinfthe other E? e control relay for the main line for causing the normal operation 'of'its said power driven-means, a reverse switch control relay for causing the reverse operation of said power driven means for both of the. track switches, a locking relay for preventingthe re 1 sponse of said power driven means to saidswitch in control; relays when such locking relay isdeenergizedfa pick up circuit "for saidlocking relay including back contacts of all said switch control relays and iront contacts of both said traflic reg lays, a stick circuitffo'r said locking relay includ ing a front contact of said locking relay; contacts which complete such circuit only while 7, said switch control relays and said track switches are Ioutoi correspondence, and front contactsof both 7 switch control relayand said reverse switch cone trol relay also in multiple with a back contactoi said one traific relay, another indicator lamp controlledloy rnultiple front contacts on said another "5'5 normal switch lcontrol relay and said reverse r means effective when piclted up to 'causethe normal and reverse operation of said switch mach e, a locking relay forpreventing theresponse offs 'd i k up circiiipr rgs id lockingrelay mama g back contacts of;said;switchcontrol relay me 7 vtacts which completesuch stick circuit I o'nly wl1ile said switch control relaymeans jan'd said 7w "a 'centralifzedtraffic controlling system railroads, mess ah; a switch machine for machine to position said track operating said track switch, a signal for governing traflic over said switch, a traflic condition relay for indicating conditions of trafiic adjacent said track switch, control relay means for governing the operation of said switch machine when energized, a lock relay for allowing said control relay means to govern said switch machine only when such lock relay is picked up and for allowing said signal to clear only when such lock relay is dropped away, a pick-up circuit for said lock relay including contacts closed only when said control relay means is deenergized and said traffic condition relay is picked up, a stick circuit for said lock relay including a front contact of said lock relay and a circuit portion closed by contacts only when said track switch is'out of correspondence with the energized condition of said control relay means.

8. In a centralized traific controlling system for railroads; a track switch included in a detector track section and operable to normal or reverse positions for setting up a plurality of routes thereover; a switch machine for operating said track switch; signals for governing traffic over said routes; control buttons identifying the ends of said routes; a lock relay; normally inactive route establishing means responsive to the joint operation of the control buttons for the opposite ends of any particular route over said track switch for causing the operation of said switch switch to set up that route, said means being effective only when said lock relay is picked up; pick-up circuit means for energizing said lock relay only when said route establishing means is tector track section is unoccupied; stick circuit means for energizing said lock relay, when it is once picked up, dependent upon the unoccupied condition of said detector track section and dependent upon correspondence between'said route establishing means and said track switch; and.

circuit means controlled by said route establishing means for clearing a signal governing traffic over said particular route in response to the operation of the control buttons forthe opposite ends of that route only after said track switch has set up that route and has been locked; whereby said locking relay is restored to a normally energized condition when the detector track sec- 7 tion becomes unoccupied if said route establishing means is restored to an inactive'condition.

9. In a centralized trafiic controlling system for railroads, a track switch included in a detector track section and operable to normal and reverse positions for setting upa plurality of routes, a switch machine for operating said track j switch, signals for I governing trafi'lc over said routes, stay-where-put entrance buttons for the ends of said routes,seli-restoring exit buttons for the ends of said routes, alock relay, normally inactive route establishing means responsive to,

the joint operation of an entrance button for the entrance end of a route and the operation of the exit button for the exit end of that route for'causing the operation of said switch machine to position said track switch to set up such route, said means being effective only when said lock relay is picked up and remainingeffective dependent upon the operatedfposition of said en-f trancebutton for such-routeiirrespective of the self-restoration of the exit button, pick-upi circuit means for energizing saidlock relay only when said route establishing means is inactive and said "detector track section is unoccupied, stick circuit means for energizing said lock relay when it is inactive and said de- "'''means is deenergized and said once picked up dependent uponthe unoccupied condition of said detector track section and dependent upon correspondence between said route establishing means and said rack switch, and circuit means controlled by said route establishing means for clearing a signal at the entrance end of said particular route in response to the operation of the entrance and exit buttons for the opposite ends of that route only after said track switch has set up that route, whereby the restoration of an entrance button'restores'the route establishing means to an inactive condition for the route which it is then governing, which restoration is efiective to restore said locking relay to an encrgized condition only when the detector track section is unoccupied.

10. In a centralized traffic controlling system for railroads, a track layout including two main line tracks connected by a crossover having two track switches one in each main line, power driven means for operating the'track switches, a normal switch control relay for the track switch in one main line for causing the normal operation of that track switch by said power driven means, another normal switch control relay for causing the normal operation of the track switch in the other main line by said power driven means; a reverse switch control relay for causing the reidentified by the ends of the different routes through said track layout, circuit means responsive to the operation of the control buttons for the opposite ends of a particular route through said track layout for energizingthat one of said switch control relays required to set up that particular route, a lock indicator lamp associated with each track switch, a traific contact associated with each track switch and closed when a route including that track switch is occupied, and circuit means for each lock indicatorlamp controlled by front contacts of the switch control relays-for the corresponding trackswitch in multiple with the traflic contact for that track switch, whereby each indicator is illuminated as soon as a switchcontrol relay is energized for such switch, and remains illuminated as long as the associated track switch is included in an occupied route although its switch control relay is then deenergized. i

11, In a centralized trafiic controlling system for railroads, a track switch included inv a detector track section, a switch machine for operating said track switch, a track relay associated with said track switch and deenergized whenever the associated track section is occupied by a train, switch control relay means effectivewhen distinctively energized for causing saidswitch machine'to'operate to a normal or reverse position, a lock relay for'preventing said switch machine from responding to said switch control relay .means when such lock relay is deenergized, pick up circuit means for initially energizing said lock relay only when said switch control relay track relay is pickedup, and stick circuit means for'energizing said lock relay, when only-it is. once pickedup, if said track switch is unlocked or isout-of correspondence with said switch control relay means and said track relay is picked up. w

1 2, In a traffic controlling system for railroads,

a section or railway track including -a;i-trac k switch, a switch machine foroperating saidtrack switch, a track relay energized; whenever said track section; is {unoccupied and deenergized whenever said track section is occupied, a signal 1 for governing trafiic over said 7 track switch, a three-position switch machine control lever normally'assuming an inactive position and capable of being actuated to normal and reverse operating positions, switch control relay means assuming distinctive normal or reverse control conditions in accordance with the normal or reverse controlling position of the switch machine control lever and assuming a deenergized inactive condition when said switch machine control lever is in an inactive position,ra lock relay, circuit means for causing said switch machine to be controlled in accordance with the normal or reverse con- 5 trolling condition of said switch control relay "gized only means only when said lock relay is picked up, pick-up circuit means for said lock relay enerwhen said track relay is picked up, saidsignal is at stop and said switch control relay means is in an inactive condition, stick circuit means for said lock relay including contacts which are opened whenever said track switch is in correspondence with said switch control relay means, said signal is cleared or said track relay is deenergized, and a signal clearing circuit for said signal energizable only when said lock relay is deenergized and said switch control relay means is in anormal or reverse control condition.

, ANDREW LANGDON. 

